Euspongia, Fasciola and Hydra belongs to phylum-Porifera, Platyhelminthes and Coelenterata, respectively. These do not contain the tube-within-tube body plan.
Tube-within-tube is a body plan in which digestive canal is present inside the body cavity have appears tube with in a tube. All animals from the phylum-Aschelminthes to Chordata have tube-within-tube body plan and may be either protostomous or deuterostomous.